Magneto-optical recording media as rewritable optical recording media have been put to practical use. However, the magneto-optical recording media suffer from such a drawback that the reproduction characteristic deteriorates when the diameter of a recording bit as a recording magnetic domain and the recording bit interval become smaller with respect to the beam diameter of a light beam which is emitted by a semiconductor laser and focused on a magneto-optical recording medium. Such a drawback arise when adjacent recording bit enters into the beam diameter of the light beam focused on a target recording bit because the entered adjacent recording bit prevents separate reproduction of individual recording bits.
In order to overcome the drawback, Japanese Publication for Unexamined Patent Application (Tokukaihei) No. 6-150418 (1994) proposes a magneto-optical recording medium constructed by placing a nonmagnetic intermediate layer between a recording layer and a readout layer which shows in-plane magnetization at room temperature and perpendicular magnetization with an increase in temperature, and is magnetostatic-coupled with the recording layer. In this structure, the recording magnetic domain information at a portion showing in-plane magnetization is masked. Therefore, even when adjacent recording bit enters into the beam diameter of the focused light beam, it is possible to separately reproduce individual recording bits.
However, according to the above-mentioned publication, Tokukaihei No. 6-150418, it was confirmed that when recording and reproduction are performed with a smaller recording bit diameter and at a smaller recording bit interval, a great magnetic field is required for recording/erasure because a leakage magnetic field produced from a magnetization in the readout layer reaches the recording layer.